Electrical resistance heaters are useful for controlling the temperature of objects of different shapes and sizes. The amount of heat, i.e. power dissipated by an electrical resistance heater, required is proportional to the size of the object. One application is to prevent the freezing of, or to thaw, pipes and tubes carrying fluids. Examples include water pipes located outdoors or underground, or in unheated interior spaces, rain gutters and downspouts, and the like. Other utilizations could include controlling the temperature of a fluid-filled line, as might be the case in an industrial or scientific process, or of fuel and oxidizer lines in a spacecraft, or of an aquarium. In many applications, a predetermined power density (watts per square inch) is desired.
Presently available resistance heaters include metal heater elements laminated between sheets of an insulating material, such as those available from Minco Products, Inc. of Minneapolis, Minn. These heaters are made in a multiplicity of fixed sizes and shapes, and predetermined resistances, in the hope that one suitable to a particular application will be available. This type of heater generally has a serpentine resistance element that covers almost the entire area of the heater so that it cannot be cut to a different size without destroying its operability. Thus, if the application changes, a different heater is needed. If a suitable one is not available, a custom-made heater is required. All this requires expenditure of extra time and money.
Accordingly, it would be desirable to have a resistance heater that would be adaptable to a variety of applications. Specifically, it is desirable to have a strip heater having a predetermined power density (and with known width, its power per unit of length) that can be simply cut to the desired size. This beneficially reduces the breadth and cost of inventory and permits virtually immediate adaptation to different applications and to changed applications.